JPS6333767B2 - - Google Patents

Description

[Detailed description of the invention]

In recent years, polyester varnishes have been widely used as electrical insulating varnishes, especially varnishes for enameled wires, because they have a relatively good balance of mechanical properties, chemical properties, electrical properties, heat resistance, and price. . However, improvements in heat resistance are needed to reduce the size and weight of electrical equipment and improve reliability, improvements in abrasion resistance to streamline coil manufacturing, improvements in thermal shock resistance to shorten the heating time of impregnated varnish, and sealing. Improvements in hydrolysis resistance due to the increase in types of equipment, etc.
Polyester wires are no longer able to meet these demands. Polyamide-imide varnishes meet these market needs. However, polyamide-imide resins are generally insoluble in inexpensive general-purpose solvents such as cresol, which necessitates the use of expensive polar solvents such as N-methyl-2-pyrrolidone, dimethylacetamide, and dimethylformamide. The disadvantage is that the varnish is expensive because the raw materials are expensive. Therefore, in order to overcome the above-mentioned drawbacks of polyester varnishes and to solve the price problem of polyamide-imide varnishes, we have also investigated making polyamide-imide resin soluble in cresols and using it as a modifier for polyester varnishes. It's been coming. However, when a cresol solution of polyamide-imide resin, which has been made soluble in cresols by using various cresol solubilizers and whose molecular weight has been lowered, is added as a modifier to polyester varnish using cresols as a solvent, the resin Due to the compatibility of these varnishes, there were problems in that turbidity and phase separation occurred in the varnish, and that films and enameled wire coatings made using this varnish lost their transparency and gloss. In order to avoid such problems, a method has been proposed in which a polyester resin and a polyamideimide resin soluble in cresols undergo a thermal reaction (Japanese Patent Application No. 55-123806). According to this method, the varnish is uniform and transparent and does not undergo phase separation, and films and enameled wire films made using this varnish are transparent and glossy. However, in this method, the polyamide-imide resin and the polyester resin are synthesized separately in advance, and then a 2-3 step process is required to heat and react the two, which is industrially disadvantageous compared to the usual one-step synthesis process. There are many points. As a result of intensive studies to address these problems, the present inventors found that polyvalent isocyanates containing isocyanurate rings, polyvalent isocyanates that do not contain isocyanurate rings, lactams, and polyvalent isocyanates containing one or more acid anhydride groups in one molecule. After reacting a polyvalent carboxylic acid or a functional derivative thereof with a polyvalent carboxylic acid or a functional derivative thereof having two or more carboxyl groups in one molecule as necessary, The inventors have discovered that a heat-resistant resin that satisfies the aforementioned market needs can be obtained in a continuous one-step synthesis process by reacting a polyhydric alcohol having the following, leading to the present invention. Polyvalent isocyanates containing isocyanurate rings, polyvalent isocyanates not containing isocyanurate rings, lactams, polyvalent carboxylic acids having one or more acid anhydride groups in one molecule, or functional derivatives thereof, which are the pre-stage reaction in the present invention. For reactions with polyhydric carboxylic acids or their functional derivatives having two or more carboxyl groups in one molecule, if necessary, the amounts of isocyanate components and acid components to be used are determined from the viewpoint of heat resistance and flexibility. The equivalent ratio of isocyanate groups to groups is preferably 0.6 to 1.5, more preferably 0.7 to 1.15. The reaction may be carried out by charging all the raw materials at the same time, or by charging them in stages depending on the purpose. The reaction temperature is preferably 170 to 220°C for the main reaction after all components have been charged. The progress of the reaction can be determined by measuring the generated carbon dioxide gas bubbles and the viscosity of the solution. Isocyanurate ring-containing polyvalent isocyanates are used as branching components and their isocyanurate ring skeleton provides excellent heat resistance. The isocyanurate ring-containing polyvalent isocyanate is used in an amount of 0 to 50 equivalents, more preferably 0.01 to 30 equivalents, based on the total isocyanate equivalents. If it exceeds 50 equivalent %, gelation may occur during synthesis, and the flexibility of the resulting resin will decrease. Moreover, if it is less than 0.01 equivalent %, the heat resistance may be insufficient depending on the purpose of use. The amount of lactam used is based on the total isocyanate equivalent.
It is preferably less than 100 equivalent %, and more preferably in the range of 1 to 40 equivalent %. The amount of lactam used is 100 equivalent%
If the amount exceeds this amount, the heat resistance of the produced resin will decrease, and if it is less than 1 equivalent %, the produced heat resistant resin will be poorly soluble in the phenolic solvent. When calculating the blending amount of lactam, 1 mole of lactam shall be treated as 1 equivalent. Although the reaction may be carried out without a solvent, it is preferable to use a solvent from the viewpoint of ease of controlling the reaction. Examples of the isocyanurate ring-containing polyvalent isocyanate include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, ethylene diisocyanate, and 1,4-tetra Aliphatic diisocyanates such as methylene diisocyanate and 1,6-hexamethylene diisocyanate, cycloaliphatic diisocyanates such as cyclobutene 1,3-diisocyanate, cyclohexane 1,3-diisocyanate, cyclohexane 1,4-diisocyanate, isophorone diisocyanate, and triphenylmethane. An isocyanurate ring-containing polyisocyanate obtained by a polymerization reaction of a polyvalent isocyanate such as -4,4',4''-triisocyanate is used. Considering heat resistance etc., tolylene diisocyanate is preferably used. , 4,4'-diphenylmethane diisocyanate, etc., or isophorone diisocyanate. It is preferable to use an isocyanurate ring-containing polyvalent isocyanate obtained by a polymerization reaction of aromatic diisocyanate such as 4,4'-diphenylmethane diisocyanate. The production of ring-containing polyvalent isocyanates is shown in Japanese Patent Application No. 148820/1983. Examples of polyvalent isocyanates that do not contain isocyanurate rings include the raw materials for the above-mentioned isocyanurate ring-containing polyisocyanates. Various polyvalent isocyanates can be used. Considering heat resistance, aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, tolylene diisocyanate, and xylene diisocyanate are preferred. Examples of lactams include 2-pyrrolidone, ω-lauryllactam, and ε-caprolactam. Considering reactivity and economic efficiency, it is preferable to use ε-caprolactam. One or more acid anhydrides in one lactam molecule. Examples of polycarboxylic acids having groups or functional derivatives thereof include trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, 1,2,3,4-butanetetracarboxylic anhydride, 1,2,3 anhydride -Butanetricarboxylic acid, 1,2,4-butanetricarboxylic anhydride, bicyclo[2,2,2]-oct anhydride
(7)-Ene-2:3,5:6-tetracarboxylic acid, etc. can be used. Examples of polycarboxylic acids having two or more carboxyl groups in one molecule or functional derivatives thereof include terephthalic acid, isophthalic acid, phthalic acid, adipic acid, succinic acid, trimesic acid, and the like. Considering performance and cost, it is preferable to use trimellitic anhydride as the polycarboxylic acid or its functional derivative having one or more acid anhydride groups in one molecule. In the present invention, the functional derivatives of polyvalent carboxylic acids mean monoanhydrides, dianhydrides, esters, amides, chlorides, etc. derived from these polyvalent carboxylic acids. In addition, in calculating the equivalent ratio, anhydride groups, esters, amides, chlorides, etc. are treated as one equivalent of carboxyl group. Examples of reaction solvents include phenolic compounds such as phenol, cresol, and xylenol, N-methyl-2-pyrrolidone, N-methyl-caprolactam, N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, and hexamethyl. Examples include phosphonamide and the like. In the second stage reaction of the present invention, that is, the step of reacting the polyamide-imide resin or polyimide resin produced in the first stage reaction with a polyhydric alcohol having two or more hydroxyl groups in one molecule, the temperature is 160°C.
~220°C is preferred, and 180~205°C is more preferred.
If the temperature is too high, the reaction system tends to gel; on the other hand, if the temperature is too low, the flexibility, thermal shock resistance, etc. of the enamelled copper wire produced using the obtained reaction product will decrease. Although the reaction may be carried out without a catalyst, it is preferable to use a catalyst that promotes the esterification or transesterification reaction, such as dibutyltin oxide, lead acetate, zinc acetate, litharge, or tetrabutyl titanate. Further, like the reaction in the previous stage, the reaction may be carried out in either a solvent system or a solvent-free system, but from the viewpoint of ease of reaction control, it is preferable to use the solvents exemplified above. Examples of polyhydric alcohols having two or more hydroxyl groups in one molecule include ethylene glycol, neopentyl glycol, 1,4-butanediol,
1,6-hexanediol, 1,6-cyclohexanedimethanol, diethylene glycol, triethylene glycol, glycerin, trimethylolpropane, tris(2-hydroxyethyl)isocyanurate, tris(2-hydroxypropyl)isocyanurate, pentaerythritol,
Examples include sorbitol and diglycerin. Considering heat resistance, 30 equivalent% of total alcohol content
It is preferable that the above is a trivalent or higher polyhydric alcohol. Methanol, ethanol, if necessary
Monohydric alcohols such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and phenoxymethanol may be used in combination. In consideration of performance and economy, it is preferable to use ethylene glycol, glycerin, and tris(2-hydroxyethyl) isocyanurate. The ratio of the polyamide-imide resin or polyimide resin obtained in the previous step (this is referred to as A) and the polyhydric alcohol having two or more hydroxyl groups in one molecule (this is referred to as B) is A/B ( mass ratio)
is preferably 90/10 to 40/60, more preferably 80/20 to 60/40. If the amount of B is too large, the heat resistance will decrease, and if the amount of A is too large, the resin concentration in the paint will decrease when used as a heat-resistant paint, which is also undesirable from the point of view of price. In addition to the various solvents mentioned above, the heat-resistant resin produced by the method of the present invention can also contain xylene,
Aromatic hydrocarbon mixture (Nippon Oil Hysol)
100, Hysol 150, etc.) to an appropriate viscosity to make a heat-resistant resin composition such as varnish for enamel cotton. The heat-resistant resin composition produced in this way can be used as is, or as necessary, epoxy resin, phenol formaldehyde resin, blocked polyisocyanate, titanate ester and its derivatives, organic acid metal salt, polyether resin, polyamide resin. Additives such as polyesterimide resin, polyhydantoin resin, alkoxy-modified amino resin, polysulfone resin, furan resin, and phenoxy resin can be added at a ratio of 0.1 to 25% by mass based on the resin content for various purposes. can. The present invention will be explained in more detail below using comparative examples and examples. Comparative example 1

[Table] The above ingredients were placed in a four-necked flask equipped with a thermometer, stirrer, and fractionator tube, heated to 150°C in a nitrogen stream, and the reaction temperature was increased to 230°C while removing methanol distilled out during the reaction. The temperature was raised over 6 hours, and the reaction was continued at the same temperature until the gelation time on a 250°C hot plate became 160 seconds or less. Cresol was added to the hot resin to make the resin concentration 40% by weight. Further, the resin solution was kept at 120°C, and 3% by weight of tetrabutyl titanate based on the resin content was gradually added, and stirring was continued for 30 minutes to obtain a polyester varnish. Example 1 Synthesis components of isocyanurate ring-containing polyisocyanate Gram tolylene diisocyanate 600 Xylene 600 2-dimethylaminoethanol (catalyst) 1.8 The above components were placed in a four-necked flask equipped with a thermometer and a stirrer, and placed in a nitrogen stream. The temperature was raised to 140℃,
At the same temperature, the content of isocyanate groups (initial concentration:
48% by weight) was reduced to 25% by weight. The infrared spectrum of this thing has 1710 cm ^-1 , 1410
Absorption of isocyanurate rings was observed at cm ^-1 ,
Absorption of isocyanate groups was observed at 2260 cm ^-1 . 223 g of the isocyanurate ring-containing polyisocyanate solution obtained in this way, 125 g of ε-caprolactam, 470 g of diphenylmethane diisocyanate, and 1035 g of cresol were heated at 160°C for 1 hour, and then 446 g of trimellitic anhydride was added and heated to 210°C.
The mixture was reacted for 6 hours to obtain a polyamide-imide resin composition. 890g of this polyamide-imide resin composition
50 g of tris(2-hydroxyethyl) isocyanurate and 1.5 g of tetrabutyl titanate were added to the mixture and reacted at 200°C for 2.5 hours. Then, dilute the resin content with an 80/20 (mass ratio) mixture of cresol and xylene to a resin concentration of 30% by mass (viscosity 33 poise), and add Bayer's blocked isocyanate desmodule CT stable to the resin content. It was added in an amount of 5% by mass. Comparative Example 2 A part of the polyamideimide resin composition obtained in Example 1 was taken and mixed with cresol/xylene (80/2
When diluted with a mixed solution of 0.0% by weight to a resin concentration of 30% by weight, the viscosity was over 1000 poise and had no fluidity at room temperature. When this was further diluted to a viscosity (33 poise) suitable for enameled wire paint, the resin concentration was 21% by weight. Example 2 75 g of tris(2-hydroxyethyl) isocyanurate and tetrabutyl titanate were added to 841 g of the polyamideimide resin composition obtained in Example 1.
1.5g was added and reacted at 200°C for 2.7 hours. Thereafter, the resin concentration was adjusted to 30% by mass in the same manner as in Example 1.
Desmodeleur CT stable and tetrabutyl titanate were added in an amount of 5% by mass and 1% by mass, respectively, based on the resin content. Example 3 31 g of Desmodeur CT stable (polyvalent isocyanate containing an isocyanurate ring), 59 g of ε-caprolactam, 150 g of diphenylmethane diisocyanate, and 263 g of cresol were heated at 160°C for 1 hour, and then 120 g of trimellitic anhydride and benzophyl anhydride were heated. 23 g of nontetracarboxylic acid was added and reacted at 210°C for 6 hours. Thereafter, 129 g of tris(2-hydroxyethyl) isocyanurate and 1.4 g of tetrabutyl titanate were further added and reacted at 200° C. for 2.8 hours. Next, the resin was diluted in the same manner as in Example 1 so that the resin concentration was 30% by mass, and 4% by mass and 2% by mass of Desmodyur CT Stable and tetrabutyl titanate were added to the resin, respectively. The paints obtained in Examples 1 to 3 and the paints obtained in Comparative Examples were applied to a copper wire with a diameter of 1 mm by a conventional method, and the furnace temperature was 300/350/400°C (inlet/center/outlet).
Table 1 shows the properties of the enamelled copper wire obtained by baking.

[Table] As is clear from a comparison of Examples 1 to 3 and Comparative Example 1, the heat-resistant resin obtained by the production method of the present invention has better thermal shock resistance and better thermal shock resistance than polyester resin.
It has excellent heat resistance (deterioration resistance), abrasion resistance, etc.
It is industrially useful and can be widely applied not only to insulated wires but also to various uses such as metal surface protection paints, films, laminated products, adhesives, and powder molded products.

Claims (1)

[Scope of Claims] 1. Polyvalent isocyanates containing isocyanurate rings, polyvalent isocyanates not containing isocyanurate rings, lactams, polyvalent carboxylic acids having one or more acid anhydride groups in one molecule, or functional derivatives thereof, and necessary It is characterized by reacting a polyhydric carboxylic acid having two or more carboxyl groups in one molecule or a functional derivative thereof according to the conditions, and then reacting a polyhydric alcohol having two or more hydroxyl groups in one molecule. A method for producing heat-resistant resin. 2. The amount of isocyanurate ring-containing polyvalent isocyanate used is 0 to 30 equivalent% of the total isocyanate equivalent.
A method for producing a heat-resistant resin according to claim 1. 3 The isocyanurate ring-containing polyvalent isocyanate is 4,4'-diphenylmethane diisocyanate,
Claim 1 is an isocyanurate ring-containing polyisocyanate obtained from tolylene diisocyanate or isophorone diisocyanate.
A method for producing a heat-resistant resin according to item 1 or 2. 4. Claim 1, wherein the polyvalent isocyanate not containing an isocyanurate ring is 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, tolylene diisocyanate or xylylene diisocyanate,
A method for producing a heat-resistant resin according to item 2 or 3. 5. Heat resistance according to claim 1, 2, 3, or 4, wherein the polyhydric carboxylic acid having one or more acid anhydride groups in one molecule or its functional derivative is trimellitic anhydride. manufacturing method of synthetic resin. 6. The method for producing a heat-resistant resin according to claim 1, 2, 3, 4, or 5, wherein the lactam is ε-caprolactam. 7 Claims 1 and 2, wherein the polyhydric alcohol having two or more hydroxyl groups in one molecule is tris(2-hydroxyethyl)isocyanurate.
A method for producing a heat-resistant resin according to item 1, 3, 4, 5, or 6.